Semiconductor device and resin for sealing a semiconductor device

ABSTRACT

There is disclosed a semiconductor device wherein electrode terminals (2), elements (6) and wires (7) are disposed on a base plate (5) of a case (4) filled with only epoxy resin (1). The epoxy resin (1) contains impurities such as halogen and alkaline metallic salts in an amount of not more than 5 ppm and has a linear expansion coefficient of 5×10 -6  to 25×10 -6  when hardened. The semiconductor device provides for direct sealing of the components, whereby its size and cost are reduced.

This is a division, of application Ser. No. 08/077,762 filed on Jun. 18,1993, now U.S. Pat. No. 5,430,330.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device whereinelectronic components disposed within a case is sealed with resin suchas an intelligent high-power module and, more particularly, to asemiconductor device which is less costly and is small in size, and to aresin to be used therefore and a method fabricating the same.

2. Description of the Background Art

Electronic components of semiconductor devices include thin-filmresistors, ICs, hybrid ICs, transistors, diodes and the like. Forincreasing the reliability of semiconductor devices under variousenvironmental conditions, the electronic components mounted on asubstrate are housed in a package. In the semiconductor art, packageshave generally been shifted toward resin packages which arc less costly.

Methods of packaging electronic components with resin include transfermolding, casting, dipping, powder coating, dropping, tabletting, pottingand the like. In particular, portions and modules having a finestructure are protected by a precoating material (partial protectivecoat) or a buffer coating material (entire protective coat).

In particular, transistors and hybrid components such as power modules,transistor modules, hybrid ICs are coated with the entire protectivecoat and are then sealed by pouring and hardening a normal liquid epoxyresin.

For example, power components are generally protected overall using as abuffer coating material a gelatinous material such as silicon gel, andthen epoxy resin or the like is poured thereon, to achieve the scaling.FIG. 2 is a cross-sectional view of a conventional resin-sealedsemiconductor device. A semiconductor device 20 comprises electrodeterminals 2, elements 6 and wires 7 which arc disposed within a case 4having a base plate 5. The electrode terminals 2, elements 6 and wires 7are mounted on the base plate 5, and silicon gel 8 arc poured so as tosurround the mounted portions of the components and bent portions 3 ofthe electrode terminals 2. Epoxy resin 1 is filled in the remaininginterior of the case 4 which overlies the silicon gel 8. Filling thewhole interior of the case 4 with only the normal epoxy resin decreasesthe reliability of the device due to the stresses generated when theresin is hardened and the effects of impurity ions. Thus the silicon gel8 serving as a buffer is used.

However, the silicon gel is costly and requires the pouring andhardening processes thereof, resulting in high costs for providing thesemiconductor device 20. Another problem is the difficulty in sizereduction in the direction of the thickness because of the two-layerstructure having the silicon gel 8 and the resin 1.

SUMMARY OF THE INVENTION

According to the present invention, a semiconductor device comprises:(a) a box-shaped case having a bottom; (b) electronic componentsdisposed on the bottom; and (c) resin filled and hardened in the casefor sealing the electronic components, the resin (c) containing (c-1) 10to 30% by weight of epoxy resin ingredient, and (c-2) 90 to 70% byweight of filler ingredient in the form of particles, the linearexpansion coefficient of the resin when hardened being 5×10⁻⁶ to25×10⁻⁶.

The semiconductor device in which the electronic components are sealeddirectly with resin without a gel layer is reduced in size and iseconomical.

In addition, the semiconductor device is fabricated easily because itdoes not require the step of pouring and hardening gel. Thesemiconductor device may include no S-bends of the electrode terminalsbecause of the small stress of the resin.

Preferably, the epoxy resin ingredient (c- 1 ) contains (c- 1-1 ) 100parts of epoxy resin; (c-1-2) ( ) to 100 parts of acid anhydride; and(c-1-3) 0.1 to 10 parts of catalyst.

Preferably, the epoxy resin (c-1-1) contains at least one materialselected from the group consisting of bisphenol A, cycloaliphatic epoxy,and bisphenol F.

Preferably, the acid anhydride (c-1-2) contains at least one materialselected from the group consisting of methyl THPA, methyl MMPA, MNA, andDDSA.

Preferably, the catalyst (c-1-3) contains at least one material selectedfrom the group consisting of imidazole derivatives, tertiary amine andmetallic salts.

Preferably, the filler ingredient (c-2) contains at least one materialselected from the group consisting of fused quartz, quartz, alumina andaluminum nitride.

Preferably, the resin (c) further contains 3 to 10% by weight of fireretardant ingredient selected from the group consisting of antimonytrioxide and bromine compounds.

Preferably, the total amount of halogen and alkaline metal ingredientcontained in the resin (c) is not more than 10 PPM.

Preferably, the thermal conductivity of the resin (c) when hardened is0.5 to 20 Kcal/m.h.°C.

Preferably, the adhesive strength under shear of the resin (c) whenhardened is 100 to 250 Kg/cm² (Fe/Fe).

Preferably, the transverse rupturing strength of the resin (c) whenhardened is 7 to 20 Kg/mm².

Preferably, the viscosity of the resin (c) is 5000 to 100000 cps (at 25°C).

Preferably, the hardening time of the resin (c) is 0.1 to 5 hours at thetemperature of 125° C.

The present invcntion is also intended for a resin for sealing asemiconductor device, the resin having a linear expansion coefficient of5×10⁻⁶ to 25×10⁻⁶ when hardened. According to the present invention, theresin comprises: (a) 10 to 30% by weight of epoxy resin ingredientcontaining (a-1) 100 parts of epoxy resin selected from the groupconsisting of bisphenol A, cycloaliphatic epoxy and bisphenol F, (a -2)0 to 100 parts of at least one acid anhydride selected from the groupconsisting of methyl THPA, methyl MMPA, MNA and DDSA, and (a-3) 0.1 to10 parts of at least one catalyst selected from the group consisting ofimidazole derivatives, tertiary amine and metallic salts; and (b) 90 to70% by weight of at least one filler ingredient in the form of particlesselected from the group consisting of fused quartz, quartz, alumina andaluminum nitride.

Since the resin of the present invention has a small linear expansioncoefficient, the electronic components of the semiconductor device, ifdirectly sealed with resin, are not stressed when the resin is hardened,causing no warpage of the semiconductor device.

Preferably the resin further comprises 3 to 10% by weight of at leastone fire retardant ingredient selected from the group consisting ofantimony trioxide and bromine compounds.

Preferably, the total amount of halogen and alkaline metal ingredientcontained in the resin is not more than 10 PPM.

Preferably, the thermal conductivity of the resin when hardened is 0.5to 20 Kcal/m.h.° C.

Preferably, the adhesive strength under shear of the resin when hardenedis 100 to 250 Kg/cm² (Fe/Fe).

Preferably, the transverse rupturing strength of the resin when hardenedis 7 to 20 Kg/mm².

Preferably, the viscosity of the resin is 5000 to 100000 cps (at 25°C.).

Preferably, the hardening time of the resin is 0.1 to 5 hours at thetemperature of 125° C.

The present invention is also intended for a method of fabricating asemiconductor device. According to the present invention, the methodcomprises the steps of: (a) disposing electronic components in a bottomof a box-shaped case; and (b) filling and hardening a resin to seal theelectronic components, the resin containing 10 to 30% by weight of epoxyresin ingredient and 90 to 70% by weight of filler ingredient in theform of particles, the linear expansion coefficient of the resin whenhardened being 5×10⁻⁶ to 25×10⁻⁶.

The method of the present invention does not comprise the step ofpouring gel, thereby requiring only a short time efficiently.

According to the present invention, the linear expansion coefficientindicates the rate of expansion per degree Celsius. For example, a5×10⁻⁶ linear expansion coefficient may be indicated as 5×10^(-6/)° C.

An object of the present invention is to provide a semiconductor devicewhich is less costly than conventional semiconductor devices and issmall in size, and a resin to be used therefore.

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a semiconductor device according toa preferred embodiment of the present invention;

FIG. 2 is a cross-sectional view of the semiconductor device accordingto another preferred embodiment of the present invention; and

FIG. 3 is a cross-sectional view of a conventional semiconductor device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Preferred Embodiment

A semiconductor device 10 shown in FIG. 1 is fabricated by the processesto be described below. As shown in FIG. 1, clements 6, wires 7 andelectrode terminals 2 are mounted within a case 4 having a base plate 5serving as a bottom. For scaling the components, the case 4 is filledwith resin I according to the present invention. Preferably, a heat sink9 is formed on the outer surface of the base plate 5 serving as thebottom of the case 4, as shown in FIG. 2.

The semiconductor device 10 is fabricated through the steps of mountingthe elements 6, wires 7 and electrode terminals 2 on the base plate 5 ofthe box-shaped case 4 and filling and hardening the resin of the presentinvention to be described in detail later in the case 4 so as to sealthe electronic components.

A resin having an ion impurity concentration of 1 PPM is provided whichis a blend of three ingredients: an epoxy resin ingredient containing,by weight, 40 parts of bisphenol A, 60 parts of cycloaliphatic epoxy, 80parts of methyl THPA and 1 part of imidazole; a filler ingredientcontaining 700 parts by weight of quartz (containing 30 wt. % of 100 μmcrushed quartz, 60 wt. % of 20 μm spherical quartz and 10 wt. % of 0.5μm spherical quartz); and a fire retardant ingredient containing, byweight, 40 parts of HBB and 20 pans of antimony trioxide. The resin thatis hardened has a linear expansion coefficient of 18×10⁻⁶, a thermalconductivity of 0.7 Kcal/m.h.°C., a drying time of three hours at thetemperature of 125° C., a transverse rupturing strength of 12 Kg/mm²,and a viscosity of 50000 cps at the temperature of 25° C. The filleringredient may be 1000 parts by weight of alumina (containing 30 wt. %of 100 μm crushed alumina, 60 wt. % of 20 μm spherical alumina, and 10wt. % of 0.5 μm spherical alumina) or 1000 parts by weight of aluminanitride (containing 30 wt. % of 100 μm crushed alumina nitride, 60 wt. %of 20 μm spherical alumina nitride, and 10 wt. % of 0.5 pm sphericalalumina nitride) in place of the 700 parts by weight of quartz. Theresin containing alumina has a purity of 1 PPM, a linear expansioncoefficient of 22×10⁻⁶, a thermal conductivity of 1.7 Kcal/m.h.° C. adrying time of three hours at the temperature of 125° C., a transverserupturing strength of 12 Kg/mm², and a viscosity of 50000 cps at thetemperature of 25° C.

Three resins for comparison are provided: a liquid epoxy resin A havingan ion impurity concentration of 10 PPM and a linear expansioncoefficient of 20×10⁻⁶ ; a liquid epoxy resin B having an ion impurityconcentration of 1 PPM and a linear expansion coefficient of 35×10⁻⁶ ;and a liquid epoxy resin C having an ion impurity concentration of 10PPM and a linear expansion coefficient of 35×10⁻⁶. Then four moduleseach mounted on the bottom of a case are provided. The foregoing fourresins (the resin using quartz of the preferred embodiment, the resin A,the resin B and the resin C) are poured into the four cases,respectively, and are hardened for three hours at the temperature of125° C., to provide the semiconductor devices 10 as shown in FIG. 1.Also provided is the conventional semiconductor device 20 of FIG. 2using the resin A and silicon gel.

The results of the experiment of the devices are shown in Table 1.

                  TABLE 1                                                         ______________________________________                                               measuring items *                                                               heat cycle                                                                              121° C.                                                                         150° C. high                                                                    0N/0FF                                            1000 cycles                                                                             2 atm.   temperature                                                                            repetitive                               packaging                                                                              -40 to 125                                                                              water    kept for 1000                                                                          test 10000                               methods  °C.                                                                              1000 hrs.                                                                              hrs.     times                                    ______________________________________                                        present  ∘                                                                           ∘                                                                          ∘                                                                          ∘                            invention                                                                     (preferred                                                                    embodiment)                                                                   resin A (for                                                                           ∘                                                                           x        ∘                                                                          x                                        comparison)                                                                   resin B (for                                                                           x         ∘                                                                          ∘                                                                          x                                        comparison)                                                                   resin C (for                                                                           x         x        ∘                                                                          x                                        comparison)                                                                   silicon gel &                                                                          ∘                                                                           x        x        x                                        resin A (for                                                                  comparison)                                                                   ______________________________________                                         * Test for leak current and breakdown voltage                                 ∘ is normal. and X is abnormal                               

Table 2 shows characteristic data of the semiconductor device of FIG. 1fabricated using the conventional resin (the conventional method (1)),the semiconductor device of FIG. 3 fabricated using the conventionalresin (the conventional method (2)), and the semiconductor device ofFIG. 1 fabricated using the resin of the present invention (the presentinvention).

                                      TABLE 2                                     __________________________________________________________________________               CONVENTIONAL                                                                            CONVENTIONAL        PRESENT                              CHARACTER- METHOD (1)                                                                              METHOD (2)                                                                              REQUIRED  INVENTION                            ISTICS     WITHOUT GEL                                                                             WITH GEL  PROPERTIES                                                                              WITHOUT GEL                          __________________________________________________________________________     1.                                                                             WIRE     x         ∘                                                                           *INCREASE IN                                                                            GOOD     ∘                 CUTOFF                       VOLTAGE                                          CHARACTER-                                                                             x         ∘                                                                           *INCREASE IN                                                                            GOOD     ∘                 ISTIC                        ELECTRO-                                         (STRESS)                     MAGNETIC                                         SHRINKAGE                                                                              x         ∘                                                                           *INCREASE IN                                                                            GOOD     ∘                 PURITY   x         ∘                                                                           TEMPERATURE                                                                             GOOD     ∘                 ELECTRIC Δ   x         *HIGHER-  INCREASED                                                                              ∘                 RESISTANCE                   DENSITY                                          SOLDER   Δ   x         PACKAGING REDUCTION                                                                              ∘                 (CHIP)                       *INCREASE IN                                                                            IN α                             CRACK                        MOISTURE                                         HYGROSCO-                                                                              Δ   x         RESISTANCE                                                                              INCREASED                                                                              ∘                 PICITY                       *HIGHER-                                         THERMAL  Δ   x         TEMPERATURE                                                                             INCREASED                                                                              ∘                 CONDUCT-                     CONDUCTION                                       IVITY                        *INCREASE IN                                     ELECTRO- ∘                                                                           x         INSULATION                                                                              PREVENTED                                                                              ∘                 MAGNETIC                     *RATIONAL-                                       VIBRATION                    IZATION                                        10.                                                                             EXPANSION                                                                              ∘                                                                           x         *COST     ELIMI-   ∘                 OF GEL                       REDUCTION NATED                                  S-BENT   ∘ ABSENT                                                                    x PRESENT *SIZE     ABSENT   ∘                 LEAD                         REDUCTION                                        DOUBLE   ∘ SINGLE                                                                    x DOUBLE  (TO OVERCOME                                                                            SINGLE   ∘                 STRUCTURE                    DRAWBACKS OF                                                                            THIN                                   REACTIVITY                                                                             ∘                                                                           x         CONVENTIONAL                                                                            NONE     ∘                 (HARDENING                   METHODS (1)                                      FAILURE)                     & (2),                                           NUMBER OF                                                                              ∘                                                                           x         MATERIAL  REDUCED  ∘                 STEPS                        STRUCTURES                                       EXTERNAL ∘                                                                           x         & PROCESSES                                                                             NONE     ∘                 IMPACT                       ARE CHANGED)                                     COST     ∘                                                                           x                   LOW      ∘               __________________________________________________________________________

The conventional semiconductor device 20 of FIG. 3 is 11 mm thick,however, the semiconductor device 10 of the present invention is reducedin size, i.e., 7 to 8 mm thick. Since the resin 1 of the semiconductordevice 10 that is hardened has a low linear expansion coefficient and asmall stress generated, the electrode terminals 2 of the semiconductordevice 10 need not have bent portions for alleviation of stresses.

According to the present invention, the epoxy resin may be employedincluding hisphenol A, hisphenol F and cycloaliphatic epoxy. Acidanhydride may be employed including methyl THPA, methyl MMPA, MNA, andDDSA. () Catalysts may be employed including imidazole derivatives,tertiary amine, and metallic salts. The filler ingredient may beemployed including fused quartz, quartz, alumina, and alumina nitride.The fire retardant ingredient may be employed including brominecompounds, antimony trioxide, and HBB.

Bisphenol A has a great strength and a strong adhesion. Cycloaliphaticepoxy has a high tracking resistance, a high purity, and a lowviscosity. Methyl THPA has a high tracking resistance, a high purity,and a low viscosity. Imidazole has a rapid hardenability. Metal saltsare noncorrosive. Fused quartz has a low linear expansion coefficient.Alumina has a high thermal conductivity. Aluminum nitride has a veryhigh thermal conductivity. HBB is less harmful.

According to the present invention, when the amount of the filleringredient of the scaling resin is less than 70% by weight, the hardenedresin has poor properties. When the amount of the filler ingredient ofthe sealing resin is more than 90% by weight, the resin is not hardenedin some cases, providing the low strength of the hardened resin and lowthermal deformation temperatures. Less than 3% by weight of fireretardant ingredient in the resin results in the flame retardantperformance of resin which is lower than the V-0 grade of UL94, so thatthe resin becomes combustible. More than 10% by weight of fire retardantingredient in the resin decreases the physical properties of thehardened resin. A smaller amount of acid anhydride in the epoxy resiningredient causes a tendency to increase the viscosity and decrease thephysical properties of the hardened resin. More than 100 parts by weightof acid anhydride provides low physical properties of the hardened resinand low thermal deformation temperatures. Less than 0.1 part by weightof catalyst in the epoxy resin ingredient required much time forhardening, and more than 10 parts by weight thereof provides lowphysical properties and low heat resistance of the hardened resin. Alinear expansion coefficient of less than 5×10⁻⁶ is preferable butimpracticable. A linear expansion coefficient of more than 25×10⁻⁶increases the stress generated, causing cutoff of aluminum wires easily.When the total amount of halogen and alkaline metal ingredient containedin the sealing resin is more than 10 PPM, corrosion and malfunction ofthe silicon chip occur when it absorbs moisture. The hardened resin, ifhaving a thermal conductivity of less than 0.5 Kcal/m.h.° C., dissipatesless heat, resulting in increase in temperature. A thermal conductivityof more than 20 Kcal/m.h.° C. of the hardened resin is preferable butalmost impracticable. When the adhesive strength under shear of thehardened resin is less than 100 kg/cm² (Fe/Fe), the case peels off or isremoved from aluminum or the chip. The adhesive strength under shear ofmore than 250 Kg/cm² is preferable but is difficult to be achieved. Whenthe transverse rupturing strength of the hardened resin is less than 7Kg/mm², cracks occur in the resin. The resins having a transverserupturing strength of more than 20 Kg/mm² when hardened are preferable,however, rare. The viscosity of the resin is more preferably less than5000 cps (at 25° C.), however, the amount of filler must be decreased toachieve it, which does not permit other preferred effects to beobtained. The resin having a viscosity of 100000 cps (at 25° C.) has apoor workability. When it takes longer than five hours to harden theresin at the temperature of 125° C., many goods in process arc maderesulting in a poor workability. When the epoxy resin has a 0-100 : 100ratio by weight of bisphenol A to cycloaliphatic epoxy, the sealingresin when hardened has a high tracking resistance and a great strengthin accordance with the present invention.

Preferably, the resin of the present invention comprises 15 to 25% byweight of epoxy resin ingredient and 85 to 75% by weight of filleringredient. A preferable linear expansion coefficient for the foregoingpurposes is 10×10⁻⁶ to 22×10⁻⁶. The epoxy resin ingredient morepreferably comprises 100 parts of epoxy resin, 50 to 100 parts of acidanhydride and 0.5 to 5 parts of catalyst. More preferably, the epoxyresin is cycloaliphatic epoxy. Preferably, bisphenol A andcycloaliphatic epoxy are used such that the weight ratio of bisphenol Ato cycloaliphatic epoxy is 0-100:100. Acid anhydride is more preferablyselected from the group consisting of methyl THPA and MNA. The catalystis more preferably selected from the group consisting of imidazolederivatives and metallic salts. The filler ingredient is more preferablyselected from the group consisting of fused quartz and alumina. Thefused quartz preferably includes crushed particles and sphericalparticles. The spherical particles include smaller and larger particlesin mixed relation. Specifically, the diameter of the crushed particlesis 3 to 30 μm, preferably 5 to 15 μm; the diameter of the smallerspherical particles is less than 3 μm; and the diameter of the largerspherical particles is 20 to 300 μm, preferably 30 to 150 μm. Thecrushed particles have excellent adhesive properties to the resiningredient to increase the strength of the resin, and the sphericalparticles provide flowability. In particular, submicron sphericalparticles provide a great degree of sliding properties. The resinpreferably contains 5 to 10% by weight of fire retardant ingredient.More preferably, the fire retardant ingredient is at least one materialselected from the group consisting of antimony trioxide and HBB. Morepreferably, the total amount of halogen and alkaline metal ingredientcontained in the resin is not more than 3 PPM. The thermal conductivityof the hardened resin for scaling is more preferably 0.7 to 2.0Kcal/m.h.° C. The adhesive strength under shear of the hardened resin ismore preferably 150 to 250 Kg/cm² (Fe/Fe). The transverse rupturingstrength of the hardened resin is more preferably 10 to 20 Kg/mm². Theviscosity of the sealing resin is more preferably 5000 to 50000 cps (at25° C.). The hardening time of the resin at the temperature of 125° C.is more preferably 0.1 to 3 hours.

While the invention has been shown and described in detail, theforegoing description is in all aspects illustrative and notrestrictive. It is therefore understood that numerous modifications andvariations can be devised without departing from the scope of theinvention.

What is claimed is:
 1. A resin for sealing a semiconductor device, saidresin having a linear expansion coefficient of 5×10⁻⁶ to 25×10⁻⁶ whenhardened, said resin comprising:(a) 10 to 30% by weight of epoxy resiningredient containing(a-1) 100 parts of epoxy resin made only of atleast one material selected from the group consisting of bisphenol A,cycloaliphatic epoxy and bisphenol f, (a-2) 0 to 100 parts of at leastone acid anhydride selected from the group consisting of methyl THPA,methyl MMPA, MNA and DDSA, and (a-3) 0.1 to 10 parts of at least onecatalyst selected from the group consisting of imidazole derivatives,tertiary amine and metallic salts; and (b) 90 to 70% by weight of atleast one filler ingredient in the form of particles selected from thegroup consisting of fused quartz, alumina and aluminum nitride.
 2. Theresin of claim 1, whereinsaid linear expansion coefficient is 10×10⁻⁶ to22×10⁻⁶.
 3. The resin of claim 2, whereinsaid epoxy resin (a-1)essentially contains cycloaliphatic epoxy.
 4. The resin of claim 3,whereinsaid acid anhydride (a-2) is at least one material selected fromthe group consisting of methyl THPA and MNA.
 5. The resin of claim 4,whereinsaid catalyst is at least one material selected from the groupconsisting of imidazole derivatives and metallic salts.
 6. The resin ofclaim 5, whereinsaid epoxy resin ingredient (a) contains 100 parts ofepoxy resin (a-1), 50 to 100 parts of acid anhydride (a-2) and 0.5 to 5parts of catalyst (a-3).
 7. The resin of claim 6, whereinsaid filleringredient (b) contains at least one material selected from the groupconsisting of fused quartz and alumina.
 8. The resin of claim 7,whereinthe amount of said epoxy resin ingredient (a) is 15 to 25% byweight and the amount of said filler ingredient (b) is 85 to 75% byweight.
 9. The resin of claim 1, further comprising3 to 10% by weight ofat least one fire retardant ingredient selected from the groupconsisting of antimony trioxide and bromine compounds.
 10. The resin ofclaim 9, whereinthe amount of said fire retardant ingredient is 5 to 10%by weight.
 11. The resin of claim 9, comprising at least one fireretardant ingredient selected from the group consisting of HBB andantimony trioxide.
 12. The resin of claim 9, whereinthe total amount ofhalogen and alkaline metal ingredient contained in said resin is notmore than 10 PPM.
 13. The resin of claim 12, whereinsaid total amount isnot more than 3 PPM.
 14. The resin of claim 12, whereinthe thermalconductivity of said resin when hardened is 0.5 to 20 Kcal/m.h.° C. 15.The resin of claim 14, whereinsaid thermal conductivity is 0.7 to 2.0Kcal/m.h.° C.
 16. The resin of claim 14, whereinthe adhesive strengthunder shear of said resin when hardened is 100 to 250 Kg/cm² (Fe/Fe).17. The resin of claim 16, whereinsaid adhesive strength under shear is150 to 250 Kg/cm² (Fe/Fe).
 18. The resin of claim 16, whereinthetransverse rupturing strength of said resin when hardened is 7 to 20Kg/mm².
 19. The resin of claim 18, whereinsaid transverse rupturingstrength is 10 to 20 Kg/mm².
 20. The resin of claim 18, whereintheviscosity of said resin is 5000 to 100000 cps (at 25° C.).
 21. The resinof claim 20, whereinsaid viscosity is 5000 to 50000 cps (at 25° C.). 22.The resin of claim 20, whereinthe hardening time of said resin is 0.1 to5 hours at the temperature of 125° C.
 23. The resin of claim 22,whereinsaid hardening time is 0.1 to 3 hours.